Greenberg, D. (1992), Education in America – A View from Sudbury Valley, Greenberg, Daniel (1992). „'Ethics' is a Course Taught By Life Experience.”. Education in America: A View from Sudbury Valley. The Sudbury Valley School. ISBN9781888947076. Retrieved June 25, 2010.
Greenberg, D. (1992), Education in America – A View from Sudbury Valley, Greenberg, Daniel (1992). „Democracy Must be Experienced to be Learned.”. Education in America: A View from Sudbury Valley. The Sudbury Valley School. ISBN9781888947076. Retrieved June 25, 2010.
Greenberg, D. (1987) The Sudbury Valley School Experience „"Back to Basics – Moral basics."”. Архивирано из оригинала 11. 05. 2011. г. Приступљено 28. 06. 2020. Retrieved June 25, 2010.
Greenberg, D. (1987) The Sudbury Valley School Experience „"Back to Basics – Moral basics."”. Архивирано из оригинала 11. 05. 2011. г. Приступљено 28. 06. 2020. Retrieved June 25, 2010.